Domain capacity planning

Plan domain count without overloading one sending domain.

Turn campaign volume into a domain plan that respects inbox-per-domain assumptions and daily domain caps.

Calculator

Model the send load.

The calculator uses domain caps from the sending policy and keeps Microsoft/Google reseller-backed options as planning placeholders only.

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Capacity recommendation

Shared SMTP control plane

Lowest-friction package for readiness-gated SMTP inboxes on managed shared capacity.

Estimated monthly cost

$288

Planning estimate only.

Monthly emails

22,500

7,500 prospects x 3 touches.

Daily send requirement

1,039

Spread across 5 send days/week.

Recommended inboxes

42

25 emails/inbox/day cap.

Recommended domains

14

3 inboxes/domain by default.

Infrastructure caps

SMTP IP capacity
2
Domain daily cap
100
IP daily cap
3,000
Warmup assumption
30 days

Per-IP utilization should stay below 80 percent before adding traffic. Scale horizontally with more IPs or domains before raising inbox caps.

Cost assumptions

Shared SMTP control plane platform planning baseline$99
42 inboxes$168
14 managed domains$21

Domain registration, taxes, discounts, support tiers, and real Microsoft/Google reseller SKUs can change the final quote.

Readiness notes

  • Treat this as a planning estimate, not a quote or deliverability guarantee.
  • Readiness gates, seed-placement evidence, and fresh SMTP/IMAP smoke tests still decide exportability.
  • GTM-managed shared SMTP capacity; IP count is a planning signal, not a line item.

Common questions

Why does domain count sometimes exceed inbox count divided by inboxes per domain?

The calculator respects both inbox density and daily domain send caps. High daily volume can require more domains even when inbox density looks acceptable.

Can I put more inboxes on one domain?

The model uses conservative defaults. Raising density should be an operator decision backed by clean reputation and readiness evidence, not a default shortcut.

Related workflows

SPF generator

Create a safe SPF record for a new sending domain.

DMARC generator

Plan DMARC policy rollout after SPF and DKIM are aligned.

Package capacity calculator

Translate capacity assumptions into a package-level planning estimate.

Inbox readiness checker

Check whether a domain is set up to support the capacity you just planned.

Next step

Add inbox and SMTP capacity assumptions to the domain plan.

Model the full package